High-voltage switch assembly



Nov. 20, 1951 W. H. GILLILAND ETAL HIGH-VOLTAGE SWITCH ASSEMBLY FiledJan. 9, 1950 5 Sheets-Sheet l Aller/lays NOV Z0, 1951 w. H. GILLILANDETAL 2,575,707

HIGH-VOLTAGE SWITCH ASSEMBLY Filed Jan. 9 1950 5 Sheets-Sheet 2/NvE/roRs 40 W/LL/AM H G/L/LA/VD F/ TZHUGH H. TURA/HAM 6 WMMSLWAttorneys NOV- 20, 1951 w. H. GILLILAND ETAL 2,575,707

HIGH-VOLTAGE SWITCH ASSEMBLY Filed Jan. 9, 1950 5 SheetsSheet 3 llll-lum 48 illu WM WMM Nov. 20, 1951 w. H. GILLILAND ETAL 2,5751707HIGH-VOLTAGE SWITCH ASSEMBLY Filed Jan. 9, 195 5 Sheets-Sheet 4 Nov. 20,195l w. H. GILLILAND ET AL HIGH-VOLTAGE SWITCH ASSEMBLY 5 Sheets-Sheet 5Filed Jan. 9 1950 W/LL/AM H. G/L/LAND F/TZHUGH H.

TURNHAM B M @n 9L arneys Afl Patented Nov. 20, 1951 HIGH-VOLTAGE SWITCHASSEMBLY William H. Gilliland and Fitzhugh H. Turnham, Birmingham. Ala.,asslgnors to USCO Power Equipment Corp., Birm ration of Alabama ingham,Ala., a corpo- Application January 9, 1950, Serial No. 137,618

18 Claims. 1

such switches and adapted to better handle high amperage current. 1

It is the general object and purpose of the present invention to provideoperating mechanism for switches of the above type which embodies anovel assembly of elements for maximum ease of operation of the switchblade, even under severe icing condition, and in which the several partsare so arranged that, after the switch blade is twisted to frictionallygrip the contacts, the maximum pressure of the blade on said contactswill be maintained and release thereof by retroactive pressure forces ofthe contacts on said blade effectively prevented.

Another object is to provide operating means for a switch bladesupported near one end for pivotal swinging movement and for rotationaltwisting movement about its own axis which comprises a motiontransmitting rocker arm and separate blade lifting and twisting links,each pivotally connected at one end to the rocker arm, with the otherend of the lifting link mounted on a pivot supported in fixed relationto the blade and the other end of the twisting link operativelyconnected to the blade to rotationally twist the blade only whenpositioned between the contacts, while the swinging movement of theswitch blade is controlled by the lifting link.

The invention has for another object to provide an adjustable universallinkage connection between the rocker arm and switch blade, whereby theextent or amount of twisting motion transmitted to the blade may beexactly adjusted and controlled in accordance with the setting of thestationary contacts.

An additional object, in one embodiment of the invention, is to providea pivotally mounted swingable support in which the switch blade issupported near one of its ends-with a rocker arm and twist transmittinglinkage connected with said support and the adjacent end of the switchblade respectively at the same side of the pivotal axis of said support,whereby in the swinging movement of the blade from closed position themajor portion of the blade swings upwardly about the pivotal axis of thesupport while the remainingportion of the blade and said linkage swings2 downwardly about said axis. to thereby partially counter-balance theweight of the blade.

An additional object of the invention resides in the provision of aswitch blade of improved construction. with novel means for rigidlyconnectingan arcing horn to the free end of the blade on the center linethereof, so that, in the twisting movement of the blade, said horn willremain in contact with the spaced parts of stationary jaw members, theconnection between the horn and blade providing increased thermalconductivity for the transmission of heat from the point of contact.

With the above and other objects in view the invention resides in theimproved operating mechanism for electric switches of the twist bladetype, and the construction and relative arrangement of its severalparts, as will hereinafterbe more fully described, illustrated in theaccompanying drawings and subsequently incorporated in the subjoinedclaims.

In the drawings wherein we have disclosed sev eral simple and practicalembodiments of the invention and `in which similar reference charactersdesignate corresponding parts throughout the several views:

Figure 1 is a side elevation of an electric switch of the twist bladetype provided with one embodi` ment of our improved operating mechanism:

Figure 2 is a fragmentary side elevation on an enlarged scale, theswitch blade being in its closed position, and the operating linksillustrated by dotted lines in their relative positions after the switchblade has been twisted;

Figure 3 is a vertical sectional view taken substantially on the line3-3 of Figure 2 showing the operating linkage in end elevation;

Figure 4 is a detail elevation showing a modification of the adjustabletwist transmitting linkage;

Figure 5 is a side elevation showing the switch blade in open position;

Figure 6 is a top plan View of the socket bearing structure for theswitch blade:

Figure 7 is an enlarged` detail plan view of the arcing horn assembly onthe free end of the switch blade;

Figure 8 is a side elevation thereof;

Figure 9 is a transverse sectional view taken on the line 9 9 of Figure8;

Figure 10 is a side elevation of a modied embodiment of the invention,designed for ultra-high voltages;

Figure 11 isa perspective view of the switch blade operatingmechanism'shown in Figure 10: Figure 12 is an end elevation thereofpartly in section;

Figure 13 is a detail vertical section taken substantially o n the linei3-I3 of Figure 10; 'and Figure 14 is an end elevation illustrating thespring adjustment.

Referring in further detail to the drawings,

and for the present, more particularly to Figures 1 to 6 thereof, upon abase structure I0 spaced stationary insulators I2 and I4 respectivelyare rigidly mounted. In laterally spaced relation from the insulator I2a rotary insulator I6 has a downwardly extending spindle rotatablysupported in a suitable bearing |8 mounted on the base structure |0.Suitable operating means (not shown) is connected with the crank 20which is rigidly fixed to the insulator I6.

p The supporting casting 22 of electrically conductive metal, for theswitch operating mechanism, is rigidly secured to the top of thestationary insulator I2 and is formed with a horizontally disposed arm24 extending over the rotary insulator I6 and in which the top spindle26 on said insulator is journalled. To this spindle one end of the crankarm 28 is securely fixed. The end of arm 24 projects laterally beyondthe spindle 26 and to the same a conductor terminal 30 is connected inthe. usual manner.

Upon the other stationary insulator I4 an electrically conductivecasting 32 is rigidly secured. Upon this casting a pair of verticallydisposed opposed resiliently yieldable contact members, indicated at 34,are mounted. In rearwardly spaced relation from the contact members apair of vertically disposed arcing horn jaw members 36 are also rigidlyfixed to the casting 32 at their lower ends and beyond said jaw membersthe conductor terminal 38 is connected to the casting 32.

To the extent above described, the mounting and arrangement of theseveral parts is substantially in accordance with conventional practice.Our improved switch blade operating mechanism is operatively supportedupon the casting 22. This casting is formed with upwardly projectingspaced side portions 40 which receive the pivot pins 42 swingablysupporting the switch blade bearing structure 44 shown in Figure 6 ofthe drawings. As shown therein, this bearing structure comprises a onepiece casting having parallel side portions 46 which are provided withopenings at one end to receive the pivot pins 42 and are integrallyconnected by longitudinally spaced bearing portions 48 in which theswitch blade 50 at one of its ends is rotatively supported. This switchblade is preferably formed from heavy gage cylindrical copper tubing andbetween the bearing portions 48 of the swingable structure 44 a collar52 is rigidly fixed to the blade and is provided with a bifurcated lug54 radially projecting outwardly and downwardly at one side of thecollar. This rotatively supported end of the switch blade is connectedby a flexible shunt 56 to the casting 22.

The other or free end of the switch blade 50 carries an arcing horn 58for engagement between and with the jaw members 36. Preferably, as shownin Figures 1, 8 and 9 of the drawings in order to obtain maximum thermalconductivity and transmission of heat from the point of contact betweenhorn 58 and jaw members 36, we provide an elongated rectangular plate 60upon which the end portion of the tubular switch blade is flattened orswaged, as indicated at 62. The plate 6D has a narrow end flange 64abutting the end edge of the flattened tube section. upon which atubular boss 66 is centrally formed to receive one end of the arcinghorn '58 which is rigidly secured against axial or rotative movement onthe center line of the blade by a set screw 68.

The plate 80 is rigidly secured against movement axially of the blade bymeans of the spaced bolts 'I0 having nuts 12 threaded thereon.

It will be seen from the above that the attened end 62 of the switchblade is strongly reinforced by the plate 60 and the opposite side edgesthereof maintained in the required predetermined spaced relationrelative to the spacing between the contact members 34 so that the sideedges of the switch blade, when in closed position, will have heavyfrictional bearing contact with the members 34. The flattening orswaging of the end of the switch blade on the arcing horn plate 60eliminates an extra joint in the path of the circuit and by reason ofthe large area of surface contact between the copper switch blade tubingand the plate 60 maximum thermal conductivity for the transmission ofheat from the point of contact of arcing horn 58 with jaw members 36 isobtained. As the horn is accurately centered with respect to the bladeit will remain in constant contact with jaw members 36 as the blade istwisted.

Upon one side portion of the casting 22 and below the pivot axis 42 ofthe bearing structure 44, a rocker arm 14 is supported at its lower endfor pivotal rocking movement about the pivot pin 16. This rocker armextends upwardly from pivot pin 16 between the side portions 46 of thebearing structure 44 and then rearwardly over said bearing structure,terminating in an upward extension l1. This rearwardly and upwardlyextending portion of the rocker arm is integrally connected by atransverse web or top wall I8 with an opposite side portion 80 ofsimilar shape or form. The free end of crank 28 is operatively connectedwith the upper end of the space side portions of rocker arm I4 by theuniversal joint units 82 and 84 and connecting rod 86.

The forward bearing portion 48 of the swingable bearing structure 44 isprovided with an upwardly projecting apertured ear 88 in which one endof a pivot pin 90 is supported, the other end of said pin beingsupported in one side portion 46 of said bearing structure. On this pinthe lower forward end of a lifting link 92 is pivotally supported. Thislink extends upwardly and rearwardly between the side portions of rockerarm 14 with which the rear end of said link is pivotally connected bythe pin 94 mounted at its ends in the side portions of the rocker arm.

The linkage for transmitting rotational or twisting movement to theswitch blade 50 includes a bifurcated clevls member 96 pivotallyconnected with one end of the pin 94 and straddling one side portion ofthe rocker arm 14. This member 96 is connected by a threaded rod 98 witha similar threaded member |00, said members being adjusted and retainedin spaced apart relation by a nut |02 on rod 98. Threaded member |00 ispivotally connected by pin |04 with the upper end of a link element |06the lower end of which is pivotally connected with the bifurcated lug 54on collar 52 by pin |08, it being noted that the axes of pins |04 and|08 are disposed at right angles to each other, thus providing auniversal linkage connection with collar 52. A slight modification ofthe twist transmitting link is shown in Figure 4 of the drawings inwhich the clevls member 96 is replaced by a knuckle sleeve IIIl mountedon the end of pin 94 between link 92 and side portion 80 ofl the rockerarm 14 and with this sleeve member I I2 threaded on rod 98 is pivotallyconnected by pin II4 having its axis disposed at right angles to pin 94and the pin |04 connecttween said contact members.

ing member to the link element |06. Thus a universal connection is alsoprovided between the lrod 98 and the rocker arm 14. It will of course beevident that a similar member 2 may be pivotally connected with member96 in the arrangement shown in Figure 3 of the drawings.

`By proper adjustment of this twist transmitting linkage the requiredamount of twist may be imparted to the switch blade in the movement ofrocker arm 'I4 so that in the closed position of the switch blade theflattened end portion 62 thereof will be disposed in a planesubstantially at right angles to the contact members 34 to exert themaximum frictional bearing pressure against said contact members.

Referring now to Figures 1 and 2 of the drawings, it will be noted thatthe linkage pivots 90 and 94 are so located relative to the pivots 42and 16 of the structure 44 and the rocker arm 14 respectively, that inthe initial portion of the upward swinging movement of the rocker armthe ends of the link elements connected with pivot 94 move upwardlyalong substantially the same arcuate path and, while the bearingstructure 44 remains stationary, the twist transmitting linkage ispulled upwardly, thereby rotatively twisting the switch blade 50 throughsubstantially 90 degrees to disrupt the frictional bearing pressure ofthe blade against contacts 34 and position the fiattened end 62 of theblade in substantially a vertical plane between said contacts. Therelative angular positions of the lifting and twist transmitting linksat this time is illustrated in dotted lines in Figure 2. In the furtherupward swinging movement of the rocker arm, this angular relationship ofthe links is maintained and the bearing structure 44 and the switchblade z50 are swung upwardly by link 92 about the pivotal axis of thebearing structure 44 to dispose the switch blade in open position, asshown Figure of the drawings.

In the downward movement of rocker arm 14 from the position of Figure 5to close the switch, the reverse of the above described operationsoccurs and, without change in the angular relation of the lifting andtwist transmitting linkage, bearing structure 44 and switch blade 50 arefirst swung downwardly about pivot 42 with the fiattened end 62 of theblade disposed in a, vertical plane until said end of the blade ispositioned beward bearing pressure against the resilient contact members34 until said end of the blade is disposed in substantially a,horizontal plane be- The lifting and twist transmitting linkage willthen be again disposed in the relative angular positions shown in fulllines in Figure 2, and it will be seen that in view of the relativepositions of the linkage pivots 90, 94 and |04, maximum bearing pressurecontact between the blade and the contacts will be maintainednotwithstanding reactionary pressure forces by the contacts against theside edges of the end 62 of the blade tending to rotate the blade andrelease or diminish said 4bearing pressure.

Referring again to Figure 5 of the drawings, it will be noted that inthe movement of the switch blade to closed position, the bladetwistinglinkage is disposed entirely outside of the lines of force transmittedby the operating connections with crank 28 through the rocker arm 14 andthat this force is applied in a direct line substantially parallel withthe path of movement of pivot 94 to the pivot of the lifting link 92.Thus, there is no tendency to twist the switch blade until it reachesits closed position between the spaced contacts 34. This feature is ofparticular importance in the case of severe icing conditions.

The above described embodiment of our invention is designed primarilyfor use in connection with electrical circuits having a current carryingcapacity of approximately 600 amperes. In Figures 10 to 13 of thedrawings we have disclosed another embodiment of the invention intendedfor use more particularly in circuits having even higher currentcarrying capacities in the order of 2000 amperes, which will now bedescribed in further detail.

In Figure 10 of the drawings the mounting and arrangement of stationaryinsulators I I6 and I8 and the rotary insulator |20 is the same as thatpreviously described. Upon the top of insulator ||6 casting |22 isrigidly secured and provided at its opposite side edges and at one endthereof with upstanding portions |24 to which a pair of parallel copperbars |26 are securely bolted as at |28 at one of their ends. These barsextend forwardly at opposite sides of the rotary insulator |20 and arealso rigidly bolted as at |30 to theA l bearing for the top spindle ofsaid insulator, to

the upper end of which a curved forwardly extending arm |32 is securelyfixed.

To the inner face of each of the bars |26 above the insulator ||6 aseries of resilient contact members |34 are secured as at |36, thecorresponding members in each of said series being arranged in opposedrelation and extending above the bars |26.

Similar copper bars |38 are also secured to opposite side portions ofthe casting |40 rigidly fixed upon the top of insulator ||0 and to theinner faces of said bars, opposed series of resilient contact members|42 are also secured in similar manner to the contacts |34. We haveshown four contact members in each series, though it will be understoodthat a greater or less number may be used. While the contact members |34and |45! may be of any approved construction, in Figure 13 l of thedrawings we have shown a preferred U- shaped form of contact having onevertical leg |44 thereof secured to the bar |30 with the otherresiliently yieldable leg |46 of the contact member extending upwardlyin spaced relation to the fixed leg |44 and terminating at its upper endin an outwardly angled portion |48. It will be understood that normallythe resiliently yieldable legs |46 of the opposed contacts extendupwardly in convergent relation to each other between the spaced bars|38. Optionally the U-shaped spring contact members |42 of Figure 13 maybe reversed so that their rounded ends face upwardly and A projectingoutwardly above bars |28.

At each end of shaft |54 a housing'l60, having a flange |6| secured toadjacent bars |28 by bolts |58, surrounds the shaft. A counter'balancingcoiled torsion spring |82 is mounted in each .housing'. A plate |84.fixed to shaft |54 as by pin |83. closes the inner end of housing |60and is formed with a projection |85 to which one end of spring |82 isanchored.

At the outer end of each housing |60 an adjustment plate |66 having ahexagonal or other non-circular boss |61 projecting through an opening|80' in the housing lso as to be available for manipulation by a tool isslidably mountedy on shaft |54 and formed with a series of peripheralnotches |68 adapted to'coact with radial lugs |69 formed on the interiorof housing |60. The outer end of torsion spring |82 is anchored to plate|68 at projection |69'.

The springs |62 resiliently resist rocking of shaft |54. When it isdesired to vary the torsional resistance of rocking of the springs, theadjustment plate |66 is pushed in far enough axially to clear lugs |69,rotated by applying a wrench to boss |61 to wind or unwind the springand then Areleased to reengage with lugs |69.

Between the arms |50, a part of a switch blade bearing structure |10 issecured on shaft |54 as by pin |1I. In this case. the switch blade is inthe form of a rectangular copper tube |12 one end of which is closed bya member formed with a stud shaft |14 extending in coaxial relation withthe switch blade. The other end of the tubular blade is closed by aplate |16 carrying the arcing horn |18 for engagement between thestationary jaw members (not shown), in the manner above described.

The bearing structure |10 below shaft |54 is formed with a bearing |80in which the stud shaft |14 of the switch blade is journalled for freerotation. To the end of shaft |14 projecting beyond the bearing |80 acollar |82 is pinned or otherwise secured as at |84 and is provided witha radially disposed upwardly projecting bifurcated lug |86 at one sideof the shaft axis.

The bearing structure |10 is also provided 'with integrally formedspaced arms |88 projecting upwardly above the shaft |54 to which theside flanges |92 of the rocker arm |90 are pivotally connected by thepin |94 supported at its oppor site ends in the arms |88. One sideflange of the rocker arm at its forward end is formed with an aperturedear |96 carrying the pivotV pin |88 to which the upper end of the twisttransmitting linkage 200 for the switch blade is connected.

.I This linkage is substantially the same as that previously describedand is connected at its lower end by pivot. pin 202 to the bifurcatedlug |86 of the collar |82.

The rocker arm |90 extends rearwardly ,from pivot pin |94 over the rod|52 and to the rea:` end of each side flange of the rocker arm, one endof a lifting link 204 is pivotally connected as at 208. The other orforward end of each oi' these links is pivotally mounted on rod |52. y

A universal joint unit 288 is connected with upwardly projecting spacedlugs 2|0 on the rear end of rocker arm |90, said unit being connected bythe rod 2|2 with a similar universal joint unit 2|4 connected with therear end of the curved arm |32 xed to the upper end of the spindle ofthe rotary insulator |20.

when the switch blade m is in its closed position between the opposedcontacts |84 and |42,

one of the greater diameters of the rectangular blade is disposed in aplane at right angles to the contact members and the opposite corneredges of the blade have heavy frictional bearing pressure against theresilient legs |46 of the opposed contact members, as most clearly seenin Figure 13 of the drawings. Upon rotation of the rotary insulator |28to move the switch blade to open position rocker arm |90 is swungupwardly about pivot pin |94 in counterclockwlse' direction, link 204swinging upwardly with the rocker arm about the stationary pivot |52. Inthe initial part of this movement of the rocker arm, a downward thrustis applied by the linkage 200 to collar |82', thereby rotating ortwisting the switch blade |12 through substantially 90 degrees todisrupt the frictional bearing contact of the switch blade against thestationary contact members and position opposite flat side faces of theblade between and substantially' out of bearing contact with saidmembers. Thus, in the further counter-clock# wise movement of rocker arm|90 and link 204 about the fixed pivot rod |52 a downward thrust forceis applied by the rocker arm upon pivot pin |94 forwardly of thesupporting shaft |54 for the bearing structure |10 so that said bearingstructure and the switch blade as well as linkage 200 are rocked aboutthe axis of said shaft. The greater portion of the bearing structure |10to# gether with the twist transmitting linkage 200 and a part of theswitch blade is thus swung downwardly about the axis of shaft |54 whilethe remaining part of the switch blade swings upwardly and forwardlybetween the opposed contacts |34 and |42 to an open position, thustending to partially counter-balance the weight of the switch blade.

In the movement of the switch blade |12 to its closed position, rockerarm |90 and links 204 first rock in clockwise direction about the axisof pivot rod |52 as a unit so that an upward force is applied by therocker arm |90 to pivot pin |94, thereby swinging the switch blade |12downwardly around shaft |54 without change in the angular relationshipbetween the rocker arm and linkage 200 until the switch blade isdisposed in substantially horizontal position between opposed contacts|34 and |42, when opposite flat surfaces ofthe blade will be opposed tothe contacts and out of bearing engagement therewith. In the finalportion of the clockwise movement of rocker arm an angular movement ofsaid rocker member relative to link 204 about the axis of the pivot rod|52 occurs and the rocker arm then pivots about the pin |94, thusapplying a lifting force to the linkage 200 so that the switch blade |12is rotated or twisted to the position shown in Figure 13 of the drawingsto engage opposite corner edges of the blade on one of its longer diam.-eters with high frictional bearing pressure against the opposedresilient contact elements.

From the above description and the accompanying drawings, it is thoughtthat the construction, manner of operation and several advantages of thedisclosed embodiments of the invention will be fully understood. In eachof the operating mechanisms, it will be seen that we provide a novelarrangement of the linkage connections with the rocker arm so that theoperating forces are most advantageously transmitted to the switch bladeto obtain maximum ease of operation and the application of maximumpressure force by the switch blade to separate the opposed resilientcontacts. In the assembly of the blade operating mechanism, by properadjustment of the twist transmitting linkage. every 9 blade will haveexactly the required amount o twist. in accordance with the spacing ofthe opposed contact elements, to insure the application of maximumpressure force by said elements against the switch blade. Also in eachcase, the twist transmitting linkage is so arranged relative to theswitch blade and the pivotal axis of the rocker arm as to eiectivelyresist any tendency event of serious damage, can be readily replaced lat nominal expense.

'I'he invention may be embodied in other specic forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive. the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What 'is claimed and desired to be secured by United States LettersPatent is:

1. In an electric switch having a blade adapted to be twisted about itslongitudinal axis and mounted on 'a pivoted support for movementtherewith into and out of circuit closing position between a pair ofopposed contacts spaced from said support; a motion transmitting armmounted for rocking movement about a pivot axis in spaced parallelrelation to the pivotal axis of said blade support, a rst link mountedat one of its ends for swinging movement about a pivot supported infixed relation to said blade and having a pivotal connection at itsother end with said arm, a second link pivotally connected at one endwith said arm, and means connecting said second link at its other end,in spaced relation from the fixed pivot of said rst link, to said bladeto impart an axial twisting movement to said blade in relative angularmovement of said arm and links during initial rocking movement of saidarm, when the blade is in closed position, to free said blade fromfrictional engagement with the contacts, and said first link thereaftercontrolling the swinging movement of the switch blade in the continuedmovement of said rocker arm.

2. Switch mechanism comprising a supporting member, opposed stationarycontacts mounted in spaced relation to said supporting member to providean open-ended blade receiving recess, a bearing structure pivotallymounted on said supporting member, a switch blade journalled in saidbearing structure for rotational movement about its longitudinal axisand having portions of unequal cross sectional dimensions alongdifferent diameters, said blade, when in open position, being disposedwith its smaller cross sectional dimension positioned in a plane forentry between said contacts, an actuating arm rockably mounted to swingbodily around ay pivotal axis spaced from and parallel to the pivotalaxis of said bearing structure, and at least one pair of links eachhaving one end pivotally connected to said actuating arm and their otherends'being respectively pivotally connected to said bearing structureand to said switch blade, all of said link pivots having axes parallelto and spaced from thepivotal axes of said arm and bearing structure,whereby upon rocking movement of said actuating arm in one direction,said switch blade will first be bodily swung about the pivotal axis ofsaid bearing structure and positioned between said contacts and thenrotated about its longitudinal axis to dispose opposite edges of a bladeportion of major cross sectional dimension in frictional bearingengagement with said opposed contacts.

3. In an electric switch of the twist blade type having its blademounted on a support for pivotal swinging movement into and out ofengagement with a pair of opposed contacts; actuating mechanismcomprising a first pivot having its axis disposed in spaced` parallelrelation to the pivotal axis of the switch blade, a motion transmittingarm supported for rocking movement about said rst pivot, a second pivothaving its axis disposed in spaced parallel relation to said first pivotand the pivotal axis of said switch blade, said i'lrst and second pivotsbeing relatively movable, a rst link having one end pivotally mounted onsaid arm and its other end connected to said second pivot, a second linkhaving one end pivotally mounted on said arm, means pivotally connectingthe other end of said second link to the switch blade to angularly twistsaid blade, said links and first and second pivots being so arrangedthat, uponrocking movement of said motion transmitting arm in onedirection said twist blade is first moved to a closed position betweensaid opposed contacts and is then bodily twisted around its longitudinalaxis to establish high pressure circuit closing engagement of said bladewith the opposed contacts. and upon rocking movement of said arm in theopposite direction, said blade is first twisted around its longitudinalaxis to free the blade from circuit closing engagement with saidcontacts and is then swung about its pivotal axis to open position.

4. In an electric switch, an insulated contact, an insulated supportspaced from said contact,

-a pivot mounted on said support, switch blade bearing structureswingable about said pivot, a switch blade rotatably journalled near oneend in said structure and engageable near its other end with saidcontact, a second pivot spaced from and parallel to said rst pivot infixed relation to the switch blade, an actuating arm connected at oneend for rocking movement about said second pivot, a third pivot mountedin fixed relation to the bearing structure and in spaced parallelrelation to said rst and second pivots, said second and third pivotsbeing relatively movable about the axis of said rst pivot, a liftinglink pivotally connected at one end to said arm and at its other end tosaid third pivot and operable in the rocking movement of said arm toswing said bearing structure and switch blade about the axis of saidfirst pivot to and from circuit closing position with respect to saidcontact, and additional linkage operatively connecting said arm withsaid switch blade, angularly movable relative to said lifting linkduring a portion of the rocking movement of said arm in each directionto rotate the blade about its longitudinal axis and establish or releasecircuit closing pressure engagement between the switch blade andcontact. l

5. An electric switch as defined in claim 4 wherein said lifting'linkand additional linkage are swingable with the bearing structure relativeto said first pivot. l

6. An electric switch as defined in claim 4 wherein said third pivot iscarried by said bearing structure for movement therewith relative tosaid iirst and second pivots.

7. An electric switch as defined in claim 6, wherein said lifting linkand additional linkage have a common pivotal connection with saidactuating arm.

8. An electric switch as deiined in claim 4, wherein said additionallinkage connects the actuating arm adjacent to said second pivot to theend of the switch blade projecting beyond said bearing structure.

9. In an electric switch, a pair ofxopposed insu-i lated contacts, aninsulated support spaced from said contacts, a switch ,blade bearingstructure mounted for swinging movement about a fixed pivot on saidsupport, a switch blade rotatably journalled near one end in saidstructure and having a rectangular portion at its other end for movementto and from circuit closing position between said opposed contacts, anactuating arm mounted for rocking movement on said support about an axisin spaced parallel relation to the pivotal axis of said bearingstructure, a lifting link pivotally connected at opposite ends to saidactuating arm and bearing structure respectively to swing said bearingstructure and switch blade to and from circuit closing position, asecond link connected at one end to said actuating arm for angularmovement relative to said rst link, and means operatively connectingsaid second link withl said switch blade, operative to rotate said bladewhen in circuit closing position to establish or release circuitclosing/pressure engagement between said rectangular portion of theblade and said opposed contacts.

10. An electric switch as dened in claim 9. wherein said last namedmeans comprises relatively adjustable parts for determining the angularrelation of said rectangular blade portion to the contacts when incircuit closing position.

11. An electric switch as dened in claim 9. wherein said rst and secondnamed links have a common pivotal connection with said actuating arm.

12. In an electric switch of the twist blade type, a tubularelectrically conductive switch blade, actuating mechanism operativelyconnected with one end of said switch blade to swing the same about axed pivot axis and to rotate said blade about its longitudinal axis toestablish and disestablish circuit closing engagement of said blade atits other end with opposed contact members, a rectangular arcing hornplate enclosed within the latter end of said tubular switch blade, saidend portion of the blade being swaged or iiattened upon said plate inintimate heat transmitting contact therewith and having a major crosssectional dimension exceeding the diameter of the remaining portion ofthe blade, an arcing horn, and means rigidly connecting said horn tosaid plate in coaxially centered relation with the switch blade.

13. In an electric switch, spaced pairs of opposed insulated contacts, asupport, a switch blade bearing structure mounted forv pivotal swingingmovement on said support, a switch Y 12 blade rotatably journalled nearone end in said support and having rectangular portions for movement toand from circuit closing position between said opposed contacts, anactuating arm pivotally mounted at one end for rocking movement on saidbearing structure, a fixed pivot on said support, a lifting link mountedat one end on said pivot and pivotally connected with the other end ofsaid actuating arm, and means operatively connecting said actuating armadjacent to its pivoted end to said switch bladeat the opposite side ofthe pivotal axis of said bearing structure with respect to the pivotalconnection between said lifting link and actuating arm, to rotate theswitch blade when in circuit closing position between the opposedcontacts and establish or release circuit closing pressure engagementbetween the rectangular portion of the blade and said contacts.

14. An electric switch as defined in claim 13, wherein said last namedmeans comprises an adjustable linkage connection between said actuatingarm and the end of the switch blade projecting beyond said bearingstructure.

15. An electric switch as deiined in claim 13, wherein the axis of saidfixed pivot and the pivotal axis of said bearing structure are locatedin a common plane perpendicular to said support.

16. In an electric switch having a 'blade adapted to be twisted aboutits longitudinal axis and mounted on a pivoted support for movementtherewith into and out of circuit closing position between a pair ofopposed contacts; a motion transmitting arm mounted for rocking movementabout a pivot axis in spaced parallel relation to the pivotal axis ofsaid blade support, a pair of links having a common pivotal connectionat one of their ends with said arm, means pivotally connecting the otherend of one of said links with said pivoted support, and means pivotallyconnecting the other end of the other of said links with said blade,whereby in the rocking movement of said arm in one direction said linksare independently actuated to rst twist the blade and free the same fromfrictional engagement with said contacts and thereafter bodily swingsaid blade about the axis of said support to open-circuit position.

17. An electric switch as dened in claim 16, wherein said motiontransmitting arm has a portionpof channel form partially receiving andshielding the link connected with said support when the arm is incircuit closing position.

18. An electric switch as defined in claim 16 wherein the connectingmeans between said other link and said blade includes relativelyadjustable parts operable to predetermine the degree of twist and theangular position of the blade relative to the contacts when the blade isin circuit closing position.

WILLIAM H. GILLILAND. FITZHUGH H. TURNHAM.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Caldwell Apr. 5. 1949

